I soon found that the work I was doing ____ by someone else — in other words, I was wasting my time

Was it two years ago _____ they first met? [ ]

It is reported that the sandstorm is moving_______ the south year after year.

I missed the first part of the film .It was really a pity.—You ________home half an hour earlier.

Dr Bethune came to China ______the Chinese soldiers and gave his life to ____Chinese.